More than 7bn bags were handed out by seven main supermarkets in the year before the charge, but this figure plummeted to slightly more than 500m in the first six months after the charge was introduced, the Department for Environment, Food and Rural Affairs (Defra) said.

The data is the government’s first official assessment of the impact of the charge, which was introduced to help reduce litter and protect wildlife - and the expected full-year drop of 6bn bags was hailed by ministers as a sign that it is working.